Anisotropic strain-driven magnetoelectric devices

Patent metadata

Field	Value
Publication number	US-11189780-B2
Application number	US-201916387898-A
Country	US
Kind code	B2
Filing date	Apr 18, 2019
Priority date	Apr 18, 2019
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

Magnetoelectric devices based on piezoelectric/magnetostrictive bilayers are provided. Also provided are methods of using the devices to modulate or to sense the magnetization of the magnetostrictive material. The devices include an island of magnetostrictive material that is strain-coupled to a thin layer of a piezoelectric material at an interface. A bottom electrode is placed in electrical communication with one surface of the piezoelectric film, and an unpaired top electrode is placed in electrical communication with a second, opposing surface of the piezoelectric film.

First claim

What is claimed is:

1. A magnetoelectric device comprising:
a layer of piezoelectric material having a first surface and a second surface, wherein the first surface is disposed opposite the second surface;
an island of magnetostrictive material that is strain-coupled to the layer of piezoelectric material;
a bottom electrode in electrical communication with the first surface of the layer of piezoelectric material; and
an unpaired top electrode in electrical communication with the second surface of the layer of piezoelectric material, wherein the island of magnetostrictive material is disposed on the unpaired top electrode or wherein the island of magnetostrictive material is disposed adjacent to the unpaired top electrode and the island of magnetostrictive material and the adjacent unpaired top electrode are both disposed on the second surface of the layer of piezoelectric material, and further wherein the bottom electrode and the unpaired top electrode are configured to apply or to detect an electric field through a thickness of the layer of piezoelectric material in a biased region in the layer of piezoelectric material, wherein the biased region in the piezoelectric material has an aspect ratio greater than one and is embedded in and surrounded around all lateral sides by an unbiased region in the layer of the piezoelectric material.

2. The magnetoelectric device of claim 1 , wherein the island of magnetostrictive material is disposed on the unpaired top electrode.

3. The magnetoelectric device of claim 1 , wherein the island of magnetostrictive material is disposed adjacent to the unpaired top electrode.

4. The magnetoelectric device of claim 1 , further comprising a substrate, wherein the layer of piezoelectric material is not clamped to a substrate.

5. The magnetoelectric device of claim 1 , wherein the piezoelectric material is Pb(Mg 1/3 Nb 2/3 )O 3 ] 0.7 —[PbTiO 3 ] 0.3 .

6. The magnetoelectric device of claim 1 , wherein the bottom electrode and the unpaired top electrode are configured to apply the electric field through the thickness of the layer of piezoelectric material in the biased region.

7. The magnetoelectric device of claim 1 , wherein the bottom electrode and the unpaired top electrode are configured to detect the electric field through the thickness of the layer of piezoelectric material in the biased region.

8. The magnetoelectric device of claim 1 , wherein the layer of piezoelectric material has a thickness in the range from 100 nm to 1 μm.

9. The magnetoelectric device of claim 8 further comprising a substrate underlying the bottom electrode, wherein the substrate does not prevent in-plane strain from being freely generated in the layer of piezoelectric material.

10. The magnetoelectric device of claim 9 , wherein the substrate comprises a polymer and the bottom electrode is on the polymer.

11. A magnetoelectric device array comprising:
a plurality of magnetoelectric devices, each magnetoelectric device in the plurality comprising:
a layer of piezoelectric material having a first surface and a second surface, wherein the first surface is disposed opposite the second surface;
an island of magnetostrictive material that is strain-coupled to a layer of piezoelectric material;
a bottom electrode in electrical communication with the first surface of the layer of piezoelectric material; and
an unpaired top electrode in electrical communication with the second surface of the layer of piezoelectric material, wherein the island of magnetostrictive material is disposed on the unpaired top electrode or wherein the island of magnetostrictive material is disposed adjacent to the unpaired top electrode and the island of magnetostrictive material and the adjacent unpaired top electrode are both disposed on the second surface of the layer of piezoelectric material, and further wherein the bottom electrode and the unpaired top electrode are configured to apply or to detect an electric field through a thickness of the layer of piezoelectric material in a biased region in the layer of piezoelectric material, wherein the biased region in the piezoelectric material has an aspect ratio greater than one and is embedded in and surrounded around all lateral sides by an unbiased region in the layer of the piezoelectric material.

12. A method of reorienting the direction of magnetization in a magnetostrictive material in a device comprising:
a bilayer comprising:
a layer of piezoelectric material having a first surface and a second surface, wherein the first surface is disposed opposite the second surface; and
an island of magnetostrictive material that is strain-coupled to the layer of piezoelectric material,

a bottom electrode in electrical communication with the first surface of the layer of piezoelectric material; and
an unpaired top electrode in electrical communication with the second surface of the layer of piezoelectric material, wherein the island of magnetostrictive material is disposed on the unpaired top electrode or wherein the island of magnetostrictive material is disposed adjacent to the unpaired top electrode and the island of magnetostrictive material and the adjacent unpaired top electrode are both disposed on the second surface of the layer of piezoelectric material, and further wherein the bottom electrode and the unpaired top electrode are configured to apply the out-of-plane electric field through a thickness of the layer of piezoelectric material,
the method comprising:
applying an out-of-plane electric field through the thickness of the layer of piezoelectric material, wherein the application of the out-of-plane electric field creates a biased region having an aspect ratio greater than one embedded in the layer of piezoelectric material and surrounded on all lateral sides by an unbiased region in the layer of piezoelectric material and induces the direction of magnetization in the magnetostrictive material to undergo an in-plane rotation from a first in-plane direction to a second in-plane direction.

13. The method of claim 12 , wherein the island of magnetostrictive material is disposed on the unpaired top electrode.

14. The method of claim 12 , wherein the island of magnetostrictive material is disposed adjacent to the unpaired top electrode.

15. The method of claim 12 , wherein the layer of piezoelectric film is not clamped to a substrate.

16. The method of claim 12 , wherein the piezoelectric material is Pb(Mg 1/3 Nb 2/3 )O 3 ] 0.7 —[PbTiO 3 ] 0.3 .

17. The method of claim 12 , wherein the in-plane rotation is a 90° in-plane rotation.

18. A method of sensing the direction of magnetization in a magnetostrictive material in a device comprising:
a bilayer comprising:
a layer of piezoelectric material having a first surface and a second surface, wherein the first surface is disposed opposite the second surface; and
an island of magnetostrictive material that is strain-coupled to the layer of piezoelectric material,

a bottom electrode in electrical communication with the first surface of the layer of piezoelectric material; and
an unpaired top electrode in electrical communication with the second surface of the layer of piezoelectric material, wherein the island of magnetostrictive material is disposed on the unpaired top electrode or wherein the island of magnetostrictive material is disposed adjacent to the unpaired top electrode and the island of magnetostrictive material and the adjacent unpaired top electrode are both disposed on the second surface of the layer of piezoelectric material, and further wherein the bot

Assignees

• Wisconsin Alumni Res Found

Inventors

• Eom Chang-Beom
• Rzchowski Mark Steven
• Irwin Julian James
• Lindeman Shane Martin

Classifications

• G01R33/18

  Measuring magnetostrictive properties · CPC title

• G01R33/1215 Primary

  Measuring magnetisation; Particular magnetometers therefor (G01R33/14 takes precedence; electrodynamic magnetometers G01R33/028) · CPC title

• H01L27/20

  Electricity · mapped topic

• H01L41/12

  Electricity · mapped topic

• H01L43/12

  Electricity · mapped topic